Figure 2.

Proliferating, and not resting, T cells are highly sensitive to CDDO-mediated apoptosis. CFSE-labeled BALB/c splenocytes were incubated with irradiated T cell-depleted B6 splenocytes at a 1:1 ratio with a dose range of CDDO as described in Materials and Methods. After 3 days in culture, cells were harvested and analyzed by flow cytometry. Cells were first gated on CD4 or CD8 expression, then gated on CFSE^high or CFSE^low staining, and analyzed for annexin V binding in proliferating or resting T cells. (A) Proportionally greater increases in annexin V binding were observed on proliferating (CFSE^low) compared with nonalloreactive (CFSE^high) CD4⁺ T cells with exposure to 0.25 μM, 0.5 μM, and 0.75 μM CDDO. (B) Proportionally greater increases in annexin V binding were observed on proliferating (CFSE^low) compared with nonalloreactive (CFSE^high) CD8⁺ T cells with exposure to 0.25 μM, 0.5 μM, and 0.75 μM CDDO. *Significant differences of annexin V binding on CDDO-exposed T cells compared with control (P < 0.05). Results from 1 of 3 independent experiments are presented.